The present invention relates to an installation provided with a device for lining up pipes or pipe components, such as for example T-pieces and the like. The line up device ensures that one end of a pipe or component is positioned in such a manner with respect to a free end of a fixed pipe or component that these ends can then be connected to one another by means of a welded joint, a bolt connection or other mechanical connection, for example.
Line up devices of the mentioned type are used in the construction of pipelines which are employed to transport petroleum or natural gas and for water injection.
A known application area is the laying of pipelines at sea from a vessel. Known methods for this purpose include the J-lay, S-lay and the Reel-lay methods, which are described in GB 2 335 722 A. The vessel is provided with an installation which comprises one or more connection stations, such as welding stations, for connecting various pipes or pipe components. The installation is also provided with a line up device in order to bring the pipes into line with one another.
A known line up device comprises two gripper means each having two movable clamping jaws which are arranged on a frame. These gripper means are positioned at a distance from one another in the axial direction of a pipe.
At the same time, the gripper means can be moved along a pipe receiving structure in the axial direction of the clamped pipe, in order to securely grip the pipe and to transport an end of this pipe to a short distance from the free end of a second, fixedly held pipe, so that a gap remains between the two ends or the ends touch one another.
In order then to line up the end of the fixedly held pipe and the first pipe with respect to one another, the clamped end of the first pipe can be moved in a plane which is perpendicular to the axial direction of the first pipe.
In a subsequent step, the clamped end of the first pipe is positioned against the end of the fixed pipe by moving the two gripper means simultaneously over a short distance in the axial direction towards the fixed pipe. Then, the two ends are welded together or are connected in some other way.
The installation which has been described is suitable for lining up and connecting single-walled pipes and pipe components. In many cases, however, it is desirable to construct double-walled pipes, i.e. xe2x80x9cpipe-in-pipexe2x80x9d pipes. The inner pipe of the double-walled pipe is in many cases in the offshore industry used to transport a liquid, such as oil, or a gas or a mixture thereof. The outer pipe serves as a protective pipe against external water pressure, inter alia. A thermal insulation means may be arranged between the inner pipe and the outer pipe, in order to ensure that the medium in the inner pipe is not cooled excessively by external conditions.
The object of the invention is to provide an installation as described in the preamble which is suitable for lining up double walled pipes.
This object is achieved by at least one of the gripper means being designed to alternately securely grip an inner pipe and an outer pipe of a double-walled pipe.
In this way, the following method can be carried out. Firstly, the outer pipe of a first double-walled pipe is gripped by a first gripper means. Then, an end of the inner pipe of the first double-walled pipe which is projecting out of the outer pipe is gripped by a second gripper means. This second gripper means is then moved, bringing the inner pipe with it, in the axial direction towards the end of an inner pipe of a fixed, second double-walled pipe. In the process, the inner pipe and the outer pipe of the first double-walled pipe are displaced with respect to one another.
After the end of the inner pipe of the first double-walled pipe has been brought to a short distance from the end of the fixed inner pipe of the second double-walled pipe, the end of the inner pipe of the first double-walled pipe is ligned up by independent movement of at least one of the gripper means in a plane which is perpendicular to the axial direction of the pipes. When the inner pipes have been oriented in such a manner with respect to one another that they can be connected, the two gripper means are simultaneously moved in the axial direction, so that the inner pipes of the first and second double-walled pipes are positioned with their ends against each other. They are then connected to one another.
Next, the second gripper means releases the inner pipe of the first double-walled pipe and is displaced towards the first gripper means. If appropriate, an insulation means can then be arranged around the inner pipe.
Then, the outer pipe of the first double-walled pipe is gripped by the second gripper means and the first gripper means releases the outer pipe. The end of the outer pipe is then displaced, by means of the second gripper means, until it is close to the end of the fixed outer pipe of the second double-walled pipe.
Then, the outer pipe of the first double-walled pipe is in turn gripped by the first gripper means, after which the end of the outer pipe can be ligned up with the fixed outer pipe of the second pipe by moving the gripper means as described above. Next, the outer pipes are placed against one another as a result of the two gripper means being moved simultaneously towards second pipe by moving the gripper means as described above. Next, the outer pipes are placed against one another as a result of the two gripper means being moved simultaneously towards the second pipe, after which the ends of the outer pipes can be connected to one another.
The second gripper means is able to grip both an inner pipe and an outer pipe without it being necessary to adapt the second gripper means in order to enable pipes of different diameters to be gripped. This can be achieved by designing the gripper means as a clamp with a plurality of sets of shoes, it being possible to use one set of shoes to grip pipe diameters which lie between a specific minimum diameter and a specific maximum diameter.
In one embodiment, the gripper means may be arranged on a line up frame, in which case they can advance along the line up frame and the line up frame is attached to the main frame of the installation. The line up frame can be moved in the desired direction with respect to the main frame by means of actuators.
In another embodiment, the gripper means are arranged directly on the main frame and can move along it.
The present invention will be explained in more detail in the following detailed description of a preferred embodiment of an installation according to the invention and with reference to the drawing.